Conventionally, pupil modulation techniques using an LCOS-SLM (Liquid Crystal On Silicon-Spatial Light Modulator) have been known (for example, see PTL 1). A phase-modulation-type spatial light modulating device using an LCOS device can desirably change the phase distribution of light to be made to enter the pupil of an objective lens and can simultaneously form multiple spots at an image position. With an LCOS device, the sum of the energy of diffracted light transmitted through the pupil of the objective lens and the energy of light focused at the image position is constant in theory, and the power of the light can be efficiently used.